Pinpoint Test H: The Low Oil Pressure Warning Indicator Is Never/Always On
Instrumentation, Message Center and Warning Chimes
Pinpoint Test H: The Low Oil Pressure Warning Indicator Is Never/Always On
Refer to Wiring Diagram Set 60, Instrument Cluster for schematic and connector information Electrical Diagrams.
Normal Operation
The Instrument Panel Cluster (IPC) receives the engine oil pressure status from the PCM over the High Speed Controller Area Network (HS-CAN) communication bus. The PCM provides a reference voltage to the engine oil pressure switch when the ignition key is in the RUN position. With the engine running and low or no oil pressure, the engine oil pressure switch closes to ground. The PCM detects the reference voltage pulled low and sends a request to the IPC (Instrument Panel Cluster) to illuminate the low oil pressure warning indicator. With the engine running and sufficient oil pressure, the engine oil pressure switch opens. The reference voltage remains unchanged or high and sends a request to the IPC (Instrument Panel Cluster) to turn off the low oil pressure warning indicator.
If the IPC (Instrument Panel Cluster) fails to receive the oil pressure status from the PCM for 5 seconds or less, the IPC (Instrument Panel Cluster) defaults the low oil pressure warning indicator to the last state (on or off), based upon the last known good oil pressure status message. If the IPC (Instrument Panel Cluster) fails to receive the oil pressure status from the PCM for more than 5 seconds, the IPC (Instrument Panel Cluster) sets DTC U0100:00 in continuous memory and defaults the low oil pressure warning indicator active (on).
NOTE: If DTC U0100:00 sets in the IPC (Instrument Panel Cluster), other observable symptoms may be an inoperative speedometer, tachometer, or odometer.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Engine oil pressure switch
- Base engine oil pressure concern
- PCM
- IPC (Instrument Panel Cluster)
PINPOINT TEST H : THE LOW OIL PRESSURE WARNING INDICATOR IS NEVER/ALWAYS ON
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Failure to disconnect the battery when instructed results in false resistance readings.
H1 CARRY OUT THE IPC (Instrument Panel Cluster) INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC (Instrument Panel Cluster) DataLogger.
- Select the IPC (Instrument Panel Cluster) low oil pressure warning indicator (OIL_P_LOW) active command. Command the low oil pressure warning indicator on and off. Observe the low oil pressure warning indicator.
Does the low oil pressure warning indicator illuminate when commanded on and turn off when commanded off?
Yes
If the low oil pressure warning indicator is always on, GO to H2.
If the low oil pressure warning indicator is never on, GO to H5.
No
INSTALL a new IPC (Instrument Panel Cluster). REFER to Instrument Panel Cluster (IPC) Service and Repair. TEST the system for normal operation.
H2 RETRIEVE THE RECORDED DTCs FROM THE IPC (Instrument Panel Cluster) SELF-TEST
- Check for recorded IPC (Instrument Panel Cluster) DTCs from the self-test.
Is DTC U0100:00 recorded?
Yes
GO to Pinpoint Test AM Pinpoint Test AM: DTC U0100:00 and P1607:87.
No
GO to H3.
H3 CHECK FOR A STUCK CLOSED ENGINE OIL PRESSURE SWITCH
- Ignition OFF.
- Disconnect: Engine Oil Pressure Switch C103.
- Ignition ON.
- Observe the low oil pressure indicator.
Does the low oil pressure warning indicator turn off?
Yes
INSTALL a new engine oil pressure switch. TEST the system for normal operation.
No
GO to H4.
H4 CHECK THE OIL PRESSURE INPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: PCM C175E.
- Measure the resistance between the PCM C175E-25, circuit CMC24 (GY), harness side and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to H8.
No
REPAIR circuit CMC24 (GY) for a short to ground. TEST the system for normal operation.
H5 CHECK FOR A STUCK OPEN ENGINE OIL PRESSURE SWITCH
- Ignition OFF.
- Disconnect: Engine Oil Pressure Switch C103.
- NOTE: Make sure to use a good clean ground for this test step.
Connect a fused jumper wire between the engine oil pressure switch C103-1, circuit CMC24 (GY), harness side and ground.
- Ignition ON.
- Observe the low oil pressure warning indicator.
Does the low oil pressure indicator turn on?
Yes
REMOVE the jumper wire. GO to H7.
No
LEAVE the jumper wire connected. GO to H6.
H6 CHECK THE ENGINE OIL PRESSURE INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Disconnect: C175E.
- With the jumper wire in place, measure the resistance between the PCM C175E-25, circuit CMC24 (GY), harness side and ground.
Is the resistance less than 5 ohms?
Yes
REMOVE the jumper wire. GO to H8.
No
REMOVE the jumper wire. REPAIR circuit CMC24 (GY) for an open. TEST the system for normal operation.
H7 CHECK THE OIL PRESSURE
- Carry out the engine oil pressure test Oil Pressure Test.
Is the oil pressure within specification?
Yes
INSTALL a new engine oil pressure switch. TEST the system for normal operation.
No
REFER to Engine to continue diagnosis of the engine oil pressure.
H8 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO (Key ON Engine OFF) SELF-TEST
- Check the recorded PCM DTCs from the Key ON Engine OFF (KOEO) self-test.
Are any DTCs recorded?
Yes
REFER to Computers and Control Systems Information. TEST the system for normal operation.
No
GO to H9.
H9 CHECK FOR CORRECT PCM OPERATION
- Disconnect the PCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the PCM connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new PCM. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.